Instructions
Check the packaging, if the action figure is still in its original packaging. This is what will make the figure a worthwhile collectible or not. The back of the packaging that's directly behind the action figure, the backing card, should still have bright colors that haven't faded and shouldn't be creased in order to receive a high grading. Take note of how frayed or curled the edges of the packaging are as well.
Find the price tag. The original price tag should still be included on the action figure or the packaging, and ideally should be easily readable.
Look over the plastic bubble that creates the front of the packaging. An action figure that is still high-quality won't have any dents, crushed parts or yellowing of the plastic. There shouldn't be cracks in the plastic either, and it should be correctly adhered to the backing card.